Little things add upLittle things add up

By David Jack Kenny

Little things add up. A light tailwind is no big deal when taking off from a long runway, and most airplanes have been flown at or a little above their certified maximum gross weights. Density altitude impairs climb performance, but with enough unobstructed space ahead, you’ll still get there. Stringing together enough individually minor impediments, though, can create real problems.

About 2:30 p.m. on Aug. 14, 2011, a Cessna P210N taxied to Runway 20 at Burley Municipal Airport in Burley, Idaho. On board were its 42-year-old owner, his wife, and their two teenage children, as well as about 100 pounds of luggage and perhaps 107 gallons of fuel. (The airplane was equipped with an auxiliary tank in addition to the two main wing tanks.) The family planned to fly home to the Los Angeles area with just one stop, in Provo, Utah.

The pilot’s father was one of several relatives who watched him preflight the airplane, load the gear, and get his passengers settled. The engine started without difficulty; the airplane disappeared behind a hangar on its way to the runway. They next saw it accelerating in its takeoff roll.

It was a warm day—91 degrees Fahrenheit, or about 33 Celsius—and the winds, though fairly light, were out of the north-northeast. While he didn’t know much about aviation, the pilot’s father found it odd that he was taking off with a tailwind, which he estimated at 5 to 10 mph. (The airport manager later reported winds from 020 to 030 degrees at 6 knots.) The Centurion used about three-fourths of the 4,092-foot runway to become airborne, and the pilot immediately retracted the gear. Then, at an altitude estimated as just 75 feet agl and with the airplane still above the runway, he began a left turn. The airplane immediately began to descend, still banked about 30 degrees, and continued to drop until its left wingtip, belly, and propeller hit an elevated roadway just beyond the airport fence. The impact cartwheeled it onto a railroad track, where it exploded into flames.

There were no survivors, and indeed so much of the airplane was consumed by the fire that investigators had to guess at the weight of its contents. They finally concluded that while it was not significantly overloaded, it was within plus or minus 50 pounds of its 4,000-pound maximum gross, with the center of gravity within limits. The engine was heavily damaged by fire, but disassembly found no evidence of any failure prior to impact that would have kept it from producing its full 310 horsepower.

Burley Municipal sits at an elevation of 4,154 feet. The middle of a hot August afternoon might not have been the best time to depart, especially in a fully loaded airplane. The NTSB calculated that the density altitude was 7,116 feet, robbing the propeller of thrust and the wings of lift even though the turbocharged engine could still produce full power. After factoring in the 6-knot tailwind, Cessna calculated that the Centurion would have needed 4,048 feet—essentially the full length of the runway—to clear that hypothetical 50-foot obstacle … and of course that still assumes a perfectly functioning airplane flown with perfect short-field technique.

One of the traps that can catch a pilot unfamiliar with high-altitude operations is raising the nose to the familiar climb attitude rather than pitching for airspeed. This can leave the airplane mushing along on the verge of a stall, unable to realize whatever modest climb performance circumstances permit. At that point even the slight additional loading of a 30-degree bank can make it impossible to hold altitude. The record doesn’t specify how much high-elevation experience the 500-hour private pilot had, but his father had only watched him take off from Burley once before—on a “very cold” winter day. Not surprisingly, the ground roll had been much shorter and the climb much faster.

It’s not clear why the pilot chose to take off with a tailwind—the departure from Runway 02 was unobstructed—or why he began turning before he had reached a safe altitude. His father recalled that his previous departure had followed the same track, and thought he might have wanted his passengers to be able to see their family members on the ground as long as possible. If so, it was a generous impulse, but shouldn’t have taken precedence over managing a maximum-weight, high-altitude takeoff.

Six knots doesn’t sound like much—but taking off into the wind instead of with it would have reduced the distance needed to gain that first 50 feet by more than a quarter. Climbing faster would have reduced the temptation to pitch up past VX, and building both airspeed and altitude would have made it safe to turn. Little things add up.